Not enough vitamin D may boost depression risk

They say sunshine can cheer you up, but insufficient levels of the sunshine vitamin may also increase your risk of developing depression, says a joint study from Italy and the US.

Both men and women over the age of 65 have increased risk of depressive symptoms is they have low vitamin D levels, with the association stronger in women than men, according to findings published in the Journal of Clinical Endocrinology & Metabolism​.

“Understanding the potential causal pathway between vitamin D deficiency and depression requires further research,”​ wrote the researchers, led by Luigi Ferrucci from the US National Institute on Aging.

And the World Health Organization (WHO) forecasts that within 20 years more people will be affected by depression than any other health problem; it ranks depression as the leading cause of disability worldwide, with around 120 million people affected.

This is not the first time that vitamin D has been linked to symptoms of depression. Dutch scientists reported in 2008 in the Archives of General Psychiatry​ that low levels of the vitamin and higher blood levels of the parathyroid hormone (PTH) were associated with higher rates of depression among 1,282 community residents aged between 65 and 95.

Furthermore, a review by Bruce Ames and Joyce McCann from the Children's Hospital and Research Center Oakland highlighted the role of the vitamin in maintaining brain health, noting the wide distribution of vitamin D receptors throughout the brain.

According to the review (FASEB Journal​, Vol.22, pp. 982-1001), the vitamin has been reported to affect proteins in the brain known to be directly involved in learning and memory, motor control, and possibly even maternal and social behaviour. Depression in the elderly is highly prevalent and can increase the risk of medical illnesses, worsen the outcome of other medical illnesses, and may increase mortality.

Study details​

Ferrucci and his co-workers analysed data from 531 women and 423 men aged over 65 participating in the Italy-based InCHIANTI Study. The participants were followed for six years and their depressive symptoms assessed using the Center for Epidemiological Studies-Depression Scale (CES-D).

Results showed that women with blood levels of 25(OH)D – the storage form of the vitamin in the blood – below 50 nmol/litre had significantly higher scored on the CES-D, than women with vitamin D levels about 50 nmol/litre.

Similar relationships were observed in men, but the association was not as strong, said the researchers.

“Our findings suggest that hypovitaminosis D is a risk factor for the development of depressive symptoms in older persons,”​ they wrote.

However, the study does not prove causality, and further study is required.

Mood food​

The link between diet and mood may extend to a variety of nutrients, according to the literature. Scientists from around the world have reported that ingredients such as zinc, omega-3, folate, St John’s wort, green tea and red clover may reduce the symptoms of depression.